Occupational exposure of hairdressers to [ 14C]- para-phenylenediamine-containing oxidative hair dyes: A mass balance study

We monitored the exposure of hairdressers to oxidative hair dyes for 6 working days under controlled conditions. Eighteen professional hairdressers (3/day) coloured hairdresser’s training heads bearing natural human hair (hair length: approximately 30 cm) for 6 h/working day with a dark-shade oxidative hair dye containing 2% [ 14C]- para-phenylenediamine (PPD). Three separate phases of hair dyeing were monitored: (A) dye preparation/hair dyeing, (B) rinsing/shampooing/conditioning and (C) cutting/drying/styling. Ambient air and personal monitoring samples (vapours and particles), nasal and hand rinses were collected during all study phases. Urine (pre-exposure, quantitative samples for the 0–12, 12–24, 24–48 h periods after start of exposure) and blood samples (blank, 4, 8 or 24 h) were collected from all exposed subjects. Radioactivity was determined in all biological samples and study materials, tools and washing liquids, and a [ 14C]-mass balance was performed daily. No adverse events were noted during the study. Waste, equipment, gloves and coveralls contained 0.41 ± 0.16%, dye mixing bowls 2.88 ± 0.54%, hair wash 45.47 ± 2.95%, hair + scalp 53.46 ± 4.06% of the applied radioactivity, respectively. Plasma levels were below the limit of quantification (⩽10 ng PPD eq/mL). Total urinary 0–48 h excretion of [ 14C] levels ranged from a total of